Structural Control of Defect‐Bound Exciton Emission in α‐In 2 Se 3
ABSTRACT Native lattice defects strongly govern the optoelectronic properties of ‐, an emerging van der Waals material. At room temperature, its photoluminescence (PL) spectrum features a band‐edge excitonic “A” peak at 1.36 eV and a defect‐related sub‐bandgap “B” peak at 1.3 eV. While the B peak emission brightens significantly below 150 K, its exact origin and its connection to the low‐temperature phase transition of have remained unclear. Here, we demonstrate that the B peak emission originates from excitons trapped at Se vacancies. Upon cooling below 150 K, ‐ undergoes a structural transformation to the phase, which increases the localized electron density at Se vacancies and drives the brightening of the B peak emission. X‐ray photoelectron spectroscopy and a negative Seebeck coefficient confirm the presence of Se vacancies, which introduce electron doping and form a surface two‐dimensional electron gas observed using angle‐resolved photoemission spectroscopy. The trapped excitons exhibit strong electron–phonon coupling, with a PL lifetime of 28 ns and a large Huang–Rhys factor of 14. These results offer a framework for the deterministic control of defect‐bound excitons in ‐ for optoelectronics applications.
Authors
- Rahul S. Rao (ORCID: https://orcid.org/0000-0002-6415-0185)
- Sandy Adhitia Ekahana (ORCID: https://orcid.org/0000-0002-1693-8082)
- Michael A. Susner (ORCID: https://orcid.org/0000-0002-1211-8749)
- Joshua R. Hendrickson (ORCID: https://orcid.org/0000-0002-5342-0346)
- Thuc T. Mai (ORCID: https://orcid.org/0000-0002-0062-8821)
- Jyoti Katoch (ORCID: https://orcid.org/0000-0002-3678-1780)
- Nicholas R. Glavin (ORCID: https://orcid.org/0000-0002-9447-7509)
- Michael Altvater (ORCID: https://orcid.org/0000-0002-2122-5888)
- Timothy D. Gustafson (ORCID: https://orcid.org/0000-0002-5519-4610)
- Mona Zebarjadi (ORCID: https://orcid.org/0000-0002-9170-2707)
- Nguyen Tuan Hung (ORCID: https://orcid.org/0000-0003-4156-6230)
- Christopher E. Stevens (ORCID: https://orcid.org/0000-0002-5509-8610)
- Andrea N. Giordano (ORCID: https://orcid.org/0000-0001-6668-7747)
- Md Nasim Afroj Taj (ORCID: https://orcid.org/0000-0002-9542-6746)
- Aalok Tiwari (ORCID: https://orcid.org/0009-0003-6832-4220)
- Pijush Bhattacharya
- Tyler Matos
Institutions
- United States Air Force Research Laboratory (US)
- Lawrence Berkeley National Laboratory (US)
- KBR (United States) (US)
- National Taiwan University (TW)
- National Academies of Sciences, Engineering, and Medicine (US)
- Wright-Patterson Air Force Base (US)
- National Council of University Research Administrators (US)
- Solutions Through Innovative Technologies (United States) (US)
- Defense Engineering Corporation (United States) (US)
- Defense Research Associates (United States) (US)
- National Health Council (US)
- Advanced Light Source (US)
- University of Virginia (US)
- Carnegie Mellon University (US)
Publication Details
- Journal
- Advanced Optical Materials
- Published
- 2026-10-27
- DOI
- https://doi.org/10.1002/adom.71820
- Primary Topic
- 2D Materials and Applications
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- National Science Foundation
- U.S. Department of Energy
- Office of Science
- U.S. Air Force
- Division of Materials Research
- Basic Energy Sciences
- Air Force Office of Scientific Research
- Army Research Office
- Air Force Research Laboratory